PCB News - The hazards of "fingerprints" in the PCB circuit board pads and how to avoid them

The hazards of "fingerprints" in the PCB circuit board pads and how to avoid them

In the PCB circuit board industry, the "fingerprints" in the surface treatment pads are a major scourge of circuit boards, and it is also one of the main reasons for the poor scrapping of PCB circuit boards and the deterioration of end-user reliability. However, almost every link in PCB circuit board manufacturing runs through manual operations. Only when every member of the electronics manufacturing industry develops a good habit and prevents bare hands from touching the board, can the harm of fingerprints on the circuit board be reduced or eliminated. In the circuit board manufacturing process, the hands and the board contact frequently, so fingerprints have become the most difficult problem in the industry. Let's talk about the causes, hazards and avoidance methods of "fingerprints" that can lead to poor PCB circuit boards:

1. Surface treatment pad fingerprints: Fingerprints are hand sweat stains, and its main components are as follows:

1. . Water;

2. . Cosmetics and skin care products;

3. . Inorganic salts (such as Nacl, etc.);

4. . Fatty oil (non-mineral);

5. . All kinds of dirt touched by bare hands (or dirty gloves).

2. The hazards of fingerprints in the circuit board manufacturing process

1. . Touching the board with bare hands before the solder mask will cause the solder mask to fall, resulting in poor adhesion of the green oil, which will blisters and fall off during the hot air leveling;

2. . During the process from the solder mask to the packaging of the immersion gold board, touching the board surface with bare hands will cause the board surface to be unclean, resulting in poor solderability or poor bonding;

3. . The bare object touches the board in a very short time to make the copper on the board surface chemically react, causing the copper surface to oxidize. After a longer time, obvious fingerprints will appear after electroplating, and the uneven coating will cause serious defects in the appearance of the product;

4. . Printed wet film or silk-printed circuit and PCB circuit board before lamination has fingerprint grease, which can easily cause the adhesion of dry/wet film to decrease, and lead to penetration and separation of plating during electroplating, and gold plate is easy to The pattern of the board surface is formed, and the board surface is oxidized after the solder mask is completed, and the color of yin and yang appears.

If the above phenomenon is not standardized and eliminated, it will damage the qualification rate of the product and the one-time pass rate, resulting in a long production and processing cycle, a high rework rate and a low on-time delivery rate, which will damage the company's image in the eyes of customers.

3. How to prevent bare hands from touching the board is the key to radically eliminating fingerprints

1. . Every employee is required to develop a good habit of taking and releasing boards;

2. . Carry gloves and finger cots with you;

3. . Be sure to wear gloves in the process where gloves can be worn (such as cloth gloves, rubber gloves, finger cots, etc.);

4. . Lead by example, teach by example, establish a role model, and engrave a jingle in your mind: "hold the edge of the board with both hands, lay flat, palm as the axis, coaxial rotation".